1. Field of the invention
This invention relates to a digital camera and in particular to a digital camera capable of outputting image data directly to a printer and a printing system using the same.
2. Related Art
In recent years, digital cameras (still-video cameras) have been developed, sold, and finding spreading use.
The digital camera is configured to execute photoelectric conversion of image pickup light to provide image data, record the image data on a recording medium, and output the recorded image data to an external image processing system such as a personal computer (PC). The external image processing system performs print image data preparation processing and outputs the prepared print image data to a printer for printing or reproducing the picked-up image on paper.
Most digital cameras comprise each a liquid crystal display for displaying the image pickup result and the image data provided by photoelectric conversion is compressed and recorded on a recording medium. To compress the image data, normally JPEG (Joint Photographic Expert Group) standard is applied.
To select an image on a PC, a number of thumbnail images compressed in JPEG (described later) are previously input and displayed on a monitor. The picked-up image data corresponding to a selected thumbnail image is input from the digital camera and is decompressed, then displayed on the monitor. When the user recognizes it, color print image data preparation processing is performed and the image is printed at a printer connected to the PC.
The thumbnail image is a reduced image used for the user to select a desired image out of the input image data on a PC, etc. For example, assuming that the size of 1-frame image data is 680×480 pixels, the corresponding thumbnail image is reduced by thinning out the data to about 80×60 pixels; the thumbnail images are recorded on a recording medium of the digital camera in a one-to-one correspondence with normal picked-up images.
When color print image data preparation processing is performed, print image data preparation processing is performed by programs on the PC to reproduce or print a color image (video) with high accuracy and bit map data is prepared for each print color required for drawing and is given to a printer together with a control signal for performing the color image reproduction operation on recording paper.
A color print ink jet printer capable of printing a high-quality image like a picture or a photo is developed and sold as a color printer.
The above-mentioned print image data preparation processing programs are contained in a program group called a printer driver in a data processing module 210 as shown In FIG. 11. A printer driver 220 normally comprises three modules of rasterizer, color correction, and halftone as means for obtaining binary data.
However, usually the PC comprises a large number of application programs other than image (video) print processing because of general versatility. The application programs and the above-mentioned printer driver operate under the control of windows, MS-DOS, etc., (PC operating system (OS) manufactured by Microsoft Corporation).
Therefore, to perform image print processing, the user needs to enter commands as specified by the OS for reading the print processing application program and the printer driver into PC internal memory from a storage unit storing them (for example, magnetic disk) and placing them in an executable state. However, it takes time (so-called overhead time) to enter commands and read the print processing application program and the printer driver; the overhead time requires several minutes at the shortest, thus it takes time to start.
Although PCs are finding remarkable spreading use, many problems remain to be solved for users to know how to actually handle PCs; it is also pointed out that most persons who have PCs cannot master them. If they attempt to install the image (video) print processing application program and the printer driver, they may find it difficult to install the software or may not understand how to enter the commands.
The need for using an expensive PC only for the purpose of printing picked-up images involves remarkable impairment of user's convenience.
Examining demands for simplifying the print processing operation and reducing the overhead time almost to zero from the aspect of the digital camera, preferably, for example, image data can be output from the digital camera directly to a printer without intervention of a PC and a desired picked-up image can be printed on a desired number of print sheets in a desired paper size and print color mode. More preferably, an external unit to which image data is to be transmitted including a printer can be specified.